In an attempt to elucidate the interplay between GDF15 and RSU-1 in glioma cell invasion and the molecular pathway involved, we first assessed the invasion capacity of H4, SW1088 and A172 cells using a 3-dimensional (3D) spheroid formation assay in collagen (Supplementary Figure S3) following RSU-1 silencing. Here, RSU1 is linked to glioma.